Spike pulling mechanism

ABSTRACT

A spike puller head for a railroad spike pulling machine in which a pair of rigid arms are pivoted to a frame for swinging movement in a common plane about relatively spaced axes and are provided with relatively opposed spike gripping jaws. Supported on the frame for normally free movement between and in general alignment with the jaws is a central gripping element, a portion of which lies in the paths of movement of the arms. Power means interconnecting and supported solely by the arms are capable of selectively moving the arms to an operative position in which one of the arms engages and urges the central gripping element into operative gripping engagement with a spike received between said element and the other of the arms. In the preferred use of the invention, a pair of such puller heads are supported from a car movable along a railroad track, the respective heads being on opposite sides of one of the rails of the track and capable of longitudinal adjustment together with respect to the car, as well as of simultaneous transverse movement, either toward or away from the rail.

United States Patent Miller May 13, 1975 SPIKE PULLING MECHANISM [57] ABSTRACT Inventor? J- Miner, Charlotte A spike puller head for a railroad spike pulling ma- [73] Assignee: Southern Railway Company, chine in which a pair of l'lgld arms are pivoted to a Washington DC frame for swinging movement in a common plane about relatively spaced axes and are provided with rell Flledi J 1974 atively opposed spike gripping jaws, Supported on the [21] APP] NO; 475,923 frame for normally free movement between and in general allgnment with the aws 18 a central gripping element, a portion of which lies in the paths of move- [52] US. Cl 254/18; 294/106 ment f the amie power means interconnecting and [5 Cl. upported solely the arms are capable of elective);

[58] Field of Search 254/18, 21-24, moving the arms to an Operative position in which one 294/103, 104, 106 of the arms engages and urges the central gripping element into operative gripping engagement with a spike References Clted received between said element and the other of the UNITED STATES PATENTS arms.

1,489,844 4/1924 Markkulu 294/104 In the preferred use of the invention, a pair of such 3,249,334 5/1966 Sheperd 6t ill 294/104 uller heads are upported from a car movable along a 3,290,005 12/1966 Beemsterboer et al..... 254/18 railroad track the respective heads being on Opposite 3,322,456 5/l967 Strakmal et al, 294/104 Sides of one of the rails of the track andcapabie of Primary Examiner-Al Lawrence Smith Assistant Examiner-Robert C. Watson Attorney, Agent, or Firm-Watson, Cole, Grindle & Watson longitudinal adjustment together with respect to the car, as well as of simultaneous transverse movement, either toward or away from the rail.

12 Claims, 7 Drawing Figures @Z JEMED 1 31% 3,883,118

sum 10? 3 PATENTED HAY I 3 I975 SHEET P. 0F 3 III SPIKE IULLING MECHANISM This invention relates to improvmcnts in a railroad spike pulling machine of the class in which one or more spike puller heads are supported on a wheeled car for movement along the rails ofa railroad track, to be lowered into gripping engagement with the spikes which anchor the rails to the ties, and then raised to remove the spikes.

In such machines as heretofore employed, it has been necessary to locate the puller head precisely in position over each spike to be withdrawn. This has been complicated by the fact that in practice the spikes are driven through any of several differently located holes in the tie plates associated with the respective rails, so that there is normally a lack of uniformity in the positioning of the spikes.

Moreover the spikes on different sides ofa given rail, even though associated with the same tie and tie plate, are often offset with relation to each other in a direction parallel to the length of the rail, or in other words, are diagonally related on the tie plate, so that if two puller heads are used simultaneously on different sides of the rail. it is necessary in known tie puller machines, that the puller heads by positioned individually at slightly different locations along the rail in conformity with the different locations of the spikes.

With these considerations in mind, it is an important object of the present invention to provide in a tie puller machine, a novel tie puller head which requires but general positioning over the tie plate, the puller head being constructed, so as to be capable of gripping and pulling a spike located anywhere on the tie plate on its side of the rail.

Where there are two puller heads of the invention employed on opposite sides of a given rail, even through such heads are coupled together for identical and simultaneous positioning along the rail, it is a further important object to so construct and arrange the heads so that they are nevertheless capable of extracting spikes which are diagonally opposed. or in other words, in different longitudinal positions, despite the similar longitudinal positions of the heads themselves.

In addition it is a feature of the invention that, unlike the prior art in which the gripping force of the puller head is derived from the lifting force applied thereto. the gripping force is applied and controlled independently of the lifting force, and in a manner to achieve an improved gripping action on the spike.

Further in accordance with the invention, the spike puller heads are arranged in pairs in which the heads of each pair travel on opposite sides of a rail and are adjustable in opposite directions toward and away from the rail to predetermined positions in which they are adapted for engagement, either with those spikes contiguous to an engaging the rail flange, or with the more remote anchor spikes.

In accordance with the invention, the operative components of each spike puller head are mounted in a rigid frame which is supported from the railroad car by a fluid actuated cylinder arrangement capable of exerting a substantial upward pulling or extracting force after the pulling head is engaged with the spike. whereby to extract the same. Such components include a pair of rigid arms, respectively pivoted to the frame for swinging movement in a common plane about relatively spaced axes with the arms having relatively opposed spike gripping jaws at locations thereon, remote from such axes and being interconnected by power means which is supported solely by said arms for the purpose of selectively moving the arms, either to retract their gripping jaws away from each other or to urge them toward each other.

In their retracted position, the gripping jaws are normally separated by a distance which may conveniently be substantially equal to the full length of a tie plate, so as to span the tie plate in a lengthwise direction and thus to fall on opposite sides of a spike positioned anywhere along said tie plate. A central gripping element is supported on the frame for normally free movement between said gripping jaws and in the paths of movement of the respective arms, the gripping element normally being substantially centered between the arms and gripping jaws in the relatively separated or disengaged position of the jaws, so that when the puller head is brought into general registry with the tie plate, a spike driven through that tie plate will normally be positioned between one of the gripping jaws of said arms and the gripping element, as the puller head is brought into substantial registry with the tie plate and lowered onto the spike. Thus, as the gripping jaws are urged toward each other, one of the said arms engages and urges the gripping element into operative gripping engagement with the spike received between that element and the gripping jaw of the other arm.

In the accompanying drawings there is illustrated a preferred embodiment of the invention, though it will be appreciated that the invention is capable of other and different embodiments and that its several details may be modified in various ways, all within the scope of the present invention.

DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. 1 is a fragmentary plan view of a tie puller machine exemplifying the preferred embodiment of the invention.

FIG. 2 is a side elevation of the machine shown in FIG. 1, illustrating how the same is supported and moved on a railroad track.

FIG. 3 is an enlarged fragmentary plan view showing how the tie puller heads of the preferred embodiment are supported on a portable car for adjustment both laterally and longitudinally with respect to a rail along which the car moves;

FIG. 4 is a view on the line 44 of FIG. 3.

FIG. 5 is a detail side elevation of one of the spike puller heads; and,

FIGS. 6 and 7 are enlarged, detailed elevational views of a spike puller head of the invention, showing the same respectively in open position prior to engagement with a spike to be pulled. and in closed or operative position in gripping engagement with said spike.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in detail to the accompanying drawings, and first considering FIGS. 1 and 2. it will be noted that the spike puller mechanism is carried by 21 preferably self propelled car A which as shown in FIG. 2 is supported on flanged wheel B for movement along the rails C of a conventional railroad track.

Each rail C is' supported in conventional manner on a plurality of relatively spaced cross ties. each designated D through the intermediary of conventional tie plates E (FIGS. 2 and 4) through openings in which,

there are driven the usual rail holding spikes F, there being generally a rail holding spike on each side of the rail, with a portion of the head thereof overlying the base or flange of the rail R in usual manner. In addition it is customary to provide anchor spikes (not shown) in some of the tie plates E. These anchor spikes, being spaced outwardly from the rail C at predetermined and uniform distances, serve merely to secure the tie plate to its associated cross tie.

For the purpose of extracting or withdrawing the spikes F, there are provided pairs of tie puller heads 10, the respective heads of which are disposed on opposite sides of the rail as best shown in FIG. 4, so as to be capable of withdrawing the spikes from both sides of the rail.

Each of these puller heads is suspended from the car A in a manner hereinafter to be described in more detail, so that it may be lowered to the position of FIGS. 2 and 4 for operative gripping engagement with a spike to be withdrawn and then raised to effect withdrawal and subsequent release of the withdrawn spike.

Adverting now to a more detailed discussion of the car construction, the car A comprises a generally rectangular frame, including parallel longitudinal channel irons 12-12 which are cross connected by suitable transverse channel irons 14. This frame, in addition to providing means for supporting and transporting the tie puller heads, preferably has a motor G and various appurtenances mounted thereon in any conventional manner, as exemplified by the operators seat H and controls K, and the hydraulic fluid and fuel reservoirs L and M respectively, as well as various other conventional auxiliary parts, such as hydraulic pumps, valves and the like, not specifically illustrated and constituting no part of the instant invention.

Still referring to FIGS. 1 and 2, opening medially through the car frame is well, W defined by the transverse frame members 1414 and the portions of the longitudinal frame members interconnected by them. The supporting and adjusting means for the tie puller heads 10 extend through this opening.

Although but a single complete pair of tie puller heads 10, and a single Rail C are illustrated in FIGS. 1 and 2, an identical pair of tie puller heads, operating in identical manner with respect to its associated rail will preferably be disposed on the other side of the car symmetrically to the illustrated tie puller heacls'.

Referring to FIG. 2, there are supported by the car on opposite transverse sides of the well W a pair of relatively spaced transverse channel beams 15 interconnected at spaced locations by longitudinally disposed guide rods 16. Supported by slide bearings for longitudinal adjustment along these guide rods is a slide 18 of rectangular configuration including the cross members 20 interconnected by the longitudinal angle iron members 21.

Means for effecting the longitudinal adjustment of the slide 18, comprises a double acting hydraulic piston and cylinder unit, the cylinder portion 22 of which is connected by a yoke to a bracket 23 fixed on the structural channel member 15, while the piston rod 24 thereof is pivotally connected to an upstanding bracket 25 affixed to the slide 18, whereby to transmit longitudinal movement to the slide as the cylinder-piston unit 22-24 is extended and contracted. Suitable linear extension and contraction of the piston and cylinder unit is effected through a suitable hydraulic system and valve means constituting no part of the invention and therefore not illustrated.

As is best illustrated in FIGS. 3 and 4, there are mounted on the slide 18, longitudinally opposed pairs of track ways, preferably defined by relatively opposed channel iron members 2626 secured to the side frame members of the slide respectively.

Transversely movable carriages 2828 of relatively symmetrical but identical construction and arrangement, are supported by rollers 29 for transverse movement along the respective track ways, the positions of the tracks and carriages being so located as to properly support tie puller heads 10 on opposite sides of a rail along which the car is moved. Each such carriage 28 comprises a pair of end plates 3030, the rollers 29 being journalled on relatively remote sides of the respective plates for movement along these tracks. Each such carriage 28 thus is secured to and supported between the respective end plates 3030 and preferably at a slight angle to the horizontal, as shown in FIG. 4. A hydraulic cylinder 31 affixed to and projecting upwardly from each carriage has its piston rod 32 depending and movable downwardly through the carriage where its lower end is connected by pin 33 to a clevis 34 on the supporting frame 35 of its associated spike puller head 10. On the opposite sides thereof, the frame 35 includes slide bearings 3636 which are guided for movement on guide rods 38 respectively secured to and depending from the carriage 28. The carriage 28, guide rods 38 and its piston and cylinder unit 31-32 are all ,tilted and supported at a fixed acute angle to the vertical in a plane transecting the Rail C, so that the operative lower ends of the puller heads 10 may readily engage and grip the heads of rail holding spikes F, without interference from the rail head, in the operative position shown in FIG. 4.

However it is also desirable that the puller heads of each pair, as shown in FIG. 4, be adjustable in opposite directions away from the rail to predetermined positions wherein they may grip and withdraw anchor spikes extending through the tie plate at locations spaced outwardly from the rail flange.

In order to provide transverse adjustment of the respective carriages and puller heads, there is provided suitable power actuated adjusting means, here in the form of a hydraulic piston and cylinder unit 40, the opposite extremities of which are connected by pivots to brackets affixed to the respective carriages. Contraction of the unit 40 urges the carriages and puller heads to a predetermined position as in FIG. 4 in which the carriages abut against suitably located stops in appropriate positions for accurate engagement of the rail holding spikes. On the other hand extension of the power unit will cause a relative lateral movement a part of the respective carriages into abutment with suitably located stops 42 which position their rail puller heads for engagement with anchor spikes located outwardly from the flange.

As has been earlier indicated, the two rail puller heads 10-10 of each pair of identical construction and operate in identical manner, so that the following-detailed description of a single such puller head will suffice for both. Each puller head 10 comprises relatively spaced apart slide plates 44 (FIGS. 4, 6 and 7) which are relatively rigidly interconnected by cross pieces 45 at either end and to which are secured respectively the slide bearings36 for guiding the puller head during its raising and lowering movement on the guide rods 38. A clevis 46 fixedly secured to the upper extremity of the frame 35 is connected by a clevis pin 47 to the lower end of the piston rod 32 of the hydraulic cylinder 31, through which the puller head is raised and lowered.

Pivot pins 48-48 extending between and supported by the respective side plates of the frame provide means for medially fulcrumming levers 50 between the side plates for swinging movement parallel to the Rail C. The lower ends or arms of these levers are provided with relatively opposed spike gripping jaws 51-51 at cations thereon spaced from the axes of their respective fulcrums 48, while the upper arms or shanks of these levers are interconnected by, and serve as the sole means for supporting, a suitable power unit 52. The power unit, here shown in the form ofa double acting hydraulic piston and cylinder device, has its cylinder connected by pivot pin to the upper arm or shank of one lever 50 and has its piston rod extending between the frame side plates and connected by pivot 54 to the projecting upper end of the other lever 50. It will be understood that pressurized hydraulic fluid will be selectively supplied to and withdrawn from the cylinder by conventional flexible hoses and valving well known in the art and therefore not illustrated, so that the unit may be extended or contracted as desired by fluid pressure.

a In accordance with an important feature of the invention, there is provided a central gripping element 55 in the form of a pendant armor lever, swingably supported at its upper end by a pivot 56 for movement in a plane common to the swinging movement of the levers 50 and in the paths of movement of the respective levers. At its lower end, the central gripping arm 55 is formed to provide gripping jaws 5757 between and directed respectively toward the grippng jaws 5151 of the respective levers 50-50, whereby depending free end of the central arm or gripping element may cooperate with the jaw 51 of either lever for gripping and withdrawing a spike.

It is important to note that, although the upper ends of the levers 50-50 are interconnected and swingable relative to each other, under control of the power unit 52, the power unit is supported solely through its pivotal connections 53 and 54 to the upper ends of the levers, and thus is free to move with the levers. Similarly the levers 50-50 themselves are free to move about their respective fulcrums 48, together with the power unit 52 and to be relatively swung about their fulcrums by selective extension and contraction of the power unit.

It is important that the lower or operative end of the central gripping arm or element 55 is freely movable between and in general alignment with the gripping jaws, so that the outer gripping arms and the central gripping arm or element having a floating or freely movable relationship with respect to each other and to their supporting frame 35.

Because of this the puller head need be but very generally or approximately located with respect to a spike to be withdrawn in order to grip and withdraw the spike.

This will be readily apparent by reference to FIGS. 6 and 7. By reference to FIG. 6, it will be particularly noted that in the fully open or spread apart positions of the spike jaws 515l of the levers 50-50, the space between them advantageously may be substantially equal to the length of a tie plate E, so that when thus opened and brought into operative position over a tie plate, any spike F, no matter where located in a longitudinal direction on that tie p'late, will normally have its head located somewhere between the relatively open gripping aws.

The downwardly directed lower end surface 58 of the central gripping arm or element is of generally rounded or inverted dome shape as shown in FIG. 6, so that in the course of lowering the open puller head 10, should the lower end of the central gripping element happen to be centered over or encounter the generally domeshaped head of the spike S, it will be deflected or cammed to one side or the other of that spike so that, in the fully lowered position of the puller head, the spike will be received between a jaw 57 of the central gripping arm 55 and one or the other of the gripping jaws 51 of the levers 50-50.

As the power unit is then energized to close the jaws of the outer gripping arm by movement toward each other, that gripping lever or arm 50 on the side of the central gripping element 55 remote from the spike S, has a protrusion 59, exemplified by a replaceable wear plate, which will move into abutting engagement with the central arm or element 55 to urge it into gripping engagement with the spike. At the same time, theremaining lever or arm 50 will be drawn inwardly also into engagement with the spike, so that the latter'is firmly gripped between the lever last referred to Land the central gripping element, following which actuation of the lifting cylinder to raise thepuller head will fully withdraw the spike.

Manifestly by virtue of the floating ability or arrangement of both the levers 50 and the central gripping element 55, the spike F will be effectively gripped and withdrawn so long as it is located anywhere between the relatively spread apart lower ends of levers 50-50, when the latter are lowered as in FIG. 6.

In the overall operation of the invention, it will be apparent that the car A may be propelled along the rails C by its motor G and brought to a stop in a position with its spike puller heads 10 in raised position and located substantially over a tie from which the spikes are to be withdrawn.

By appropriate actuation of the control cylinder 40, the respective carriages 28 of each pair of puller heads may be drawn together in a predetermined position immediately above the flanges on opposite sides of the rail for engagement and withdrawal of the rail holding spikes. Alternatively by relative spreading of the carriages to position them against their stops 42, the respective puller heads 10-10 on opposite sides of the rail C may be appropriately positioned for engagement with anchor spikes spaced outwardly at predetermined distances from the rail flange.

In either event, assuming the car is brought to rest in a position in which the longitudinal location of the puller heads 10-10 is not in vertical registry with that of the underlying tie plate E, appropriate adjustment of each pair of puller heads may be simultaneously caused by actuation of the slide 18 from which such heads are supported, this in turn, being caused by the appropriate actuation of the piston and cylinder unit 22 associated with that slide.

Thereafter with the puller heads of each pair in fully released or' retracted position as in FIG. 6, the puller heads are lowered to substantially the level of the underlying tie plate. whereby to position the gripping jaws of levers 50-50 on opposite sides of the spike'to be withdrawn. Subsequent closing of the puller head into gripping relation with the spike is caused by appropriate actuation of the power unit 31, 32 of each puller head. Thereafter. raising of the puller head while in its gripping position will withdraw the spike. following which it may be released to fall back onto the tie or roadbed.

It is to be noted that the gripping and release functions of the puller head under the control of the hydraulic power unit 52 are completely separate and independent from the raising and lowering of the head 10 under control of the lifting cylinder 31. Thus. unlike prior arrangements in which the magnitude of the gripping force is dependent upon or derived from the pulling or raising force exerted on the puller head, the puller head of the instant invention is capable of securing and exerting a maximum grip upon the spike, prior to the commencement of the raising and spike pulling operation. Thus in most instances it is capable of successfully gripping and withdrawing even a spike in which part or all of the head has been removed or deformed. f

Further it will be appreciated that the spike will continue to be gripped and held with full gripping force until such time as it is fully withdrawn from the tie. it beingnecessary to actuate the power unit or cylinder 52. so as to spread the gripping jaws 51-51 apart before the spike is released and dropped back onto the roadbed for subsequent retrieval.

Attention is also directed to the advantageous feature of the invention in accordance with which the spreading apart of the lever jaws 51 to release the spike at the end of the withdrawal operation, serves also to angularly position the levers 50-50 and the central gripping element 55 in symmetrical relation to each other in optimum position for gripping and withdrawing a subsequent spike. To this end it will be noted that as the upper ends or shanks of the levers are drawntogether to separate their jaws 51-51, they will abut against and have their movement arrested by the pivoted upper end portion of the central lever arm or gripping element, the latter being urged by gravity to a vertical position.

Preferably at their points of such engagement or abutment, the inter-engaging edges or surfaces of the levers and central gripping element extend slightly below the pivot 56 and function to retain the pendant central arm in a vertical centered position between the levers.

I claim:

1. In a railroad spike pulling machine. a spike puller head comprising: a rigid frame; a pair of arms respectively pivoted to said frame for swinging movement in a common plane about parallel axes; said arms including relatively horizontally opposed spike gripping jaws at locations remote from their said axes; power means interconnecting said arms for selectively urging their said gripping jaws toward and away from each other;

and a central gripping element in the form of a pendant arm freely swingably suspended at its upper end from said frame, said pendant arm having gripping jaws at its lower end between and in horizontal alignment with said gripping jaws of said first mentioned arms for substantially horizontal free movemerit between said gripping jaws of said first mentioned arms.

2. The combinationof claim 1 wherein said power means comprises a fluid actuated cylinder and piston unit.

3. The combination of claim 1. wherein said power means is supported solely by said arms.

4. The combination of claim 1, including means operati\e when said gripping jaws are urged away from each other for spacing said gripping jaws substantially equidistantly from said central gripping element.

5. In a railroad pulling machine of the class in which a wheel supported car moves along the rails of a railroad track to transport a spike puller unit from one operative position to another along the track, the combination comprising:

a rigid frame supported from said car;

power means on said car for selectively raising and lowering said frame;

a pair of rigid arms respectively pivoted to said frame for angular movement in a common vertical plane about relatively parallel spaced axes;

said arms respectively including portions depending from said axes and defining relatively horizontally opposed spike gripping jaws:

a central gripping element supported on said frame for horizontal movement between said gripping jaws and in the paths of angular movement of said arms;

and power means interconnecting and supported solely by said arms for urging the depending portions of said arms toward each other to an operative gripping position in which one of said arms engages and urges saidelement into gripping engagement with a spike received between said element and the other said arm.

6. The combination of claim 5, including means operative when the jaws of said arms are retracted from each other for spacing them substantially equidistantly from the central gripping element so as to leave a space between each jaw and the central gripping element within which the head of a spike may be received.

7. In a railroad spike pulling machine, a spike puller head comprising:

a rigid frame;

a pair of normally spaced, generally vertically extending lever armss respectively medially fulcrummed to said frame for swinging movement in a common vertical plane;

the lower ends of said arms defining relatively horizontally opposed gripping jaws;

and power means interconnecting and supported solely by the upper ends of said arms for selectively swinging said arms to urge said gripping jaws toward each other:

the improvement which comprises a central arm having an upper end pivotally connected to said frame midway between said lever arms and having a depending freely swingable lower end portion between and coterminous with the lower ends of said lever arms, a portion of said central arm being in the paths of movement of the respective lever arms;

said lower end portion of the central arm having oppositely horizontally directed jaws in opposed relation to the respective gripping jaws of said lever arms for cooperation therewith;

said lower end portion of the central arm being normally spaced from the. gripping jaws of both said lever arms for free reception of a spike between said central arm and either of said lever arms.

8. The combination of claim 7 in which said lever arms are arranged symmetrically to a vertical plane containing the pivotal axis of said central arm, said central arm being normally urged by gravity into said plane of symmetry; the upper end portions of said medially fulcrummed lever arms being conformed to abut agaist said central arm on opposite sides of its said pivot to thereby arrest the swinging movement of said lever arms in positions wherein their gripping jaws are substantially equidstantly spaced from said central arm.

9. The combination of claim 8, including cam means at the lower end of said central arm for engagement with a spike to deflect said central arm to one side of the spike.

10. In a railroad spike pulling machine, a spike puller head comprising: a rigid frame; a pair of arms respectively pivoted to said frame for swinging movement in a common plane about parallel axes; said arms including relatively opposed spike gripping jaws at locations remote from their said axes; and power means interconnecting said arms for selectively urging their said gripping jaws toward and away from each other; there being a central gripping element, and means supporting said element for normally free movement in said common plane between and in general alignment with said gripping jaws and in the paths of swinging movement of said arms, for gripping reception of a spike between 10 said gripping element and either of said gripping jaws; including cam means associated with said central element for engagement with a spike to deflect said central gripping element to one side of the spike as the puller head is lowered.

11. In a railroad spike pulling machine, a spike puller head comprising: a rigid frame; a pair of arms respectively pivoted to said frame for swinging movement in a common plane about parallel axes; said arms including relatively opposed spike gripping jaws at locations remote from their said axes; and power means interconnecting said arms for selectively urging their said gripping jaws toward and away from each other; there being a central gripping element, and means supporting said element for normally free movement in said common plane between and in general alignment with said grippingjaws and in the paths of swinging movement of said arms, for gripping reception of a spike between said gripping element and either of said gripping jaws; there being means operative when said gripping jaws are urged away from each other spacing said gripping jaws substantially equi-distantly from said gripping ele ment; said last mentioned means comprising a portion of said central gripping element, positioned for arresting the movement apart of said arms at predetermined locations relative to said central gripping element.

12. The combination of claim 11, in which said central gripping element is pivotally suspended from said frame for movement by gravity to a predetermined location medially between said arms.

* l l =l= k 

1. In a railroad spike pulling machine, a spike puller head comprising: a rigid frame; a pair of arms respectively pivoted to said frame for swinging movement in a common plane about parallel axes; said arms including relatively horizontally opposed spike gripping jaws at locations remote from their said axes; power means interconnecting said arms for selectively urging their said gripping jaws toward and away from each other; and a central gripping element in the form of a pendant arm freely swingably suspended at its upper end from said frame, said pendant arm having gripping jaws at its lower end between and in horizontal alignment with said gripping jaws of said first mentioned arms for substantially horizontal free movement between said gripping jaws of said first mentioned arms.
 2. The combination of claim 1 wherein said power means comprises a fluid actuated cylinder and piston unit.
 3. The combination of claim 1, wherein said power means is supported solely by said arms.
 4. The combination of claim 1, including means operative when said gripping jaws are urged away from each other for spacing said gripping jaws substantially equidistantly from said central gripping element.
 5. In a railroad pulling machine of the class in which a wheel supported car moves along the rails of a railroad track to transport a spike puller unit from one operative position to another along the track, the combination comprising: a rigid frame supported from said car; power means on said car for selectively raising and lowering said frame; a pair of rigid arms respectively pivoted to said frame for angular movement in a common vertical plane about relatively parallel spaced axes; said arms respectively including portions depending from said axes and defining relatively horizontally opposed spike gripping jaws; a central gripping element supported on said frame for horizontal movement between said gripping jaws and in the paths of angular movement of said arms; and power means interconnecting and supported solely by said arms for urging the depending portions of said arms toward each other to an operative gripping position in which one of said arms engages and urges said element into gripping engagement with a spike received between said element and the other said arm.
 6. The combination of claim 5, including means operative when the jaws of said arms are retracted from each other for spacing them substantially equidistantly from the central gripping element so as to leave a space between each jaw and the central gripping element within which the head of a spike may be received.
 7. In a railroad spike pulling machine, a spike puller head comprising: a rigid frame; a pair of normally spaced, generally vertically extending lever armss respectively medially fulcrummed to said frame for swinging movement in a common vertical plane; the lower ends of said arms defining relatively horizontally opposed gripping jaws; and power means interconnecting and supported solely by the upper ends of said arms for selectively swinging said arms to urge said gripping jaws toward each other; the improvement which comprises a central arm having an upper end pivotally connected to said frame midway between said lever arms and having a depending freely swingable lower end portion between and coterminous with the lower ends of said lever arms, a portion of said central arm being in the paths of movement of the respective lever arms; said lower end portion of the central arm having oppositely horizontally directed jaws in opposed relation to the respective gripping jaws of said lever arms for cooperation therewith; said lower end portion of the central arm being normally spaced from the gripping jaws of both said lever arms for free reception of a spike between said central arm and either of said lever arms.
 8. The combination of claim 7 in which said lever arms are arranged symmetrically to a vertical plane containing the pivotal axis of said central arm, said central arm being normally urged by gravity into said plane of symmetry; the upper end portions of said medially fulcrummed lever arms being conformed to abut agaist said central arm on opposite sides of its said pivot to thereby arrest the swinging movement of said lever arms in positions wherein their gripping jaws are substantially equidstantly spaced from said central arm.
 9. The combination of claim 8, including cam means at the lower end of said central arm for engagement with a spike to deflect said central arm to one side of the spike.
 10. In a railroad spike pulling machine, a spike puller head comprising: a rigid frame; a pair of arms respectively pivoted to said frame for swinging movement in a common plane about parallel axes; said arms including relatively opposed spike gripping jaws at locations remote from their said axes; and power means interconnecting said arms for selectively urging their said gripping jaws toward and away from each other; there being a central gripping element, and means supporting said element for normally free movement in said common plane between and in general alignment with said gripping jaws and in the paths of swinging movement of said arms, for gripping reception of a spike between said gripping element and either of said gripping jaws; including cam means associated with said central element for engagement with a spike to deflect said central gripping element to one side of the spike as the puller head is lowered.
 11. In a railroad spike pulling machine, a spike puller head comprising: a rigid frame; a pair of arms respectively pivoted to said frame for swinging movement in a common plane about parallel axes; said arms including relatively opposed spike gripping jaws at locations remote from their said axes; and power means interconnecting said arms for selectively urging their said gripping jaws toward and away from each other; there being a central gripping element, and means supporting said element for normally free movement in said common plane between and in general alignment with said gripping jaws and in the paths of swinging movement of said arms, for gripping reception of a spike between said gripping element and either of said gripping jaws; there being means operative when said gripping jaws are urged away from each other spacing said gripping jaws substantially equi-distantly from said gripping element; said last mentioned means comprising a portion of said central gripping element, positioned for arresting the movement apart of said arms at predetermined locations relative to said central gripping element.
 12. The combination of claim 11, in which said central gripping element is pivotally suspended from said frame for movement by gravity to a predetermined location medially between said arms. 